High voltage oil circuit breaker



United States Patent .Oiitice 3,056,873 Patented Oct. 2, 1962 Extinguishing chambers for oil circuit breakers are known in which the gases from the arc during the iirst t part of a breaking action increase the gas pressure in a closed `spaceV above the oil level in the extinguishing chamber. At a certain distance between the contacts of the circuit breaker one or a plurality of outlet openings for the oil below the closed space are uncovered by the movable contact of the circuit breaker, so that the oil in this space is forced out through the openings against the arc. Thus, if the gas pressure in the closed space is not sufciently high, which happens when breaking small currents, lan attempt to break the current as it rst passes through zero may fail due t-o the dow of oil against the arc not being suihciently powerful. At high voltages the interruption may even fail completely and a persisting arc occur between the open contacts of the breaker.

The present invention relates to an oil circuit breaker comprising an extinguishing chamber especially suited for high voltages.

The extinguishing chamber is immersed in oil and provided with an inner arcing chamber which forms a channel through the extinguishing chamber. In one end of the channel a stationary contact is arranged and a movable contact can be passed into the channel through its other end to engage the stationary contact. In the wall of the extinguishing chamber oil openings are arranged so that the chamber is filled with oil to a predetermined level. The invention is characterised in that the extinguishing chamber is divided into at least two compartments, which at the top of the extinguishing chamber communicate with each other and that in the Wall of the arcing chamber along the channel inlet slots and outlet slots have been arranged in pairs and provided with back valves, so that oil can only flow through said slots from the channel through an inlet slot to the one compartment respectively from the other compartment through an outlet slot to the channel.

To obtain a flow of oil against the arc from at least two directions on the same level so that the arc is held centered it is possible to axially divide the extinguishing chamber into several compartments, e.g. four instead of two. Thereby all compartments communicate with each other at the top of the extinguishing chamber and between the channel and each compartment slots of only one or the other type are arranged alternately.

The stationary contact preferably is nozzle shaped so that the pressure in the arcing chamber at very long arcs will not be too high, or else it is arranged in an enlargement in one end of the channel so that a part of the breaking gases may pass freely out of the extinguishing chamber through or around the stationary contact.

'Ihe extinguishing chamber according to the invention has a particular advantage in that when a short circuit occurs while a normal breaking action is taking place, the extinguishing chamber is kept from exploding due to the gases around the arc being able to expand through a plurality of inlet slots along the arcing chamber. At the same time a high pressure is generated in the gas filled space above the oil in the extinguishing chamber, which pressure as the current next time passes through zero, forces an extinguishing stream of oil against the arc through the outlet slots.

The accompanying drawing shows an embodiment of the invention.

FIGURES 1 and 2 show vertical sections A-A respectively BB of an extinguishing chamber, which, as is evident from FIGURE 3 section C-C, is divided into four compartments.

In FIGURE l, 1 designates an extinguishing chamber immersed in o-il. The extinguishing chamber 1 is provided with an inner arcing chamber which forms a channel 2 through the chamber 1. In one end of the channel the stationary contact 4 is arranged in an enlargement 3. The movable contact 5 can be passed into the channel through" its other end to engage the stationary contact 4. Along the channel inlet slots 6 and outlet slots 7 provided with back valves are arranged. In the wall at the bottom of the extinguishing chamber small refilling openings 9 are arranged and at the top an oil opening 10. In FIGURE 2, 11 designates one of the Walls which divide the space between the walls of the extinguishing charnber and the arcing chamber. In the shown embodiment the wall 11 ends immediately below the oil level in the extinguishing chamber. Above the oil surface a closed annular `space 14 is arranged.

FIGURE 3 shows how, by the four walls 11, the extinguishing chamber has been divided into four compartments which are designated 12 and 12' and 13 and 13 respective. These compartments are in communication with each other at the top of the extinguishing chamber.

The extinguishing chamber operates in the following way. When the circuit breaker is opened an arc is drawn between the contacts which arc generates gas. The gas forms a bubble around the arc and forces aside the oil which, together with a certain amount of gas, is pressed through the inlet slots 6 to the compartments 12 and 12. 'I'he outlet slots 7 are at this stage of the breaking action closed by the back valves 8. When oil and gas are pressed 4into the compartments 12 and 12 the oil level below the annular space 14 rises and the air and gas in this space are compressed.

When the breaking current approaches zero the pressure in the gas bubble around the arc decreases and the oil in the compartments 13 and 13' is pressed out through the outlet slots 7 against the arc by the gas pressure in -the annular space 14. The inlet slots 6 are thereby closed.

Should the arc at the first attempt to break the current not be extinguished the inlet slots 6 are again opened as the current in the arc increases, the gas in the annular space 14 is again compressed and a new attempt to break the current takes place before the movable contact has managed to pass out of the channel 2, due to the length of said channel. The extinguishing chamber according to the invention has a further advantage in that the oil in the compartments 1'3 and 13 during the breaking action is not mixed with gas bubbles so that a higher extinguishing effect is obtained when this pure oil is pressed against the arc.

In the open position of the circuit breaker the extinguishing chamber is refilled with oil which flows in through the openings 9. To ensure that the oil below the annular space will, after an interruption, always rise to the same level, the extinguishing chamber is provided with oil openings 10.

I claim:

1. An oil circuit breaker comprising an extinguishing chamber immersed in oil, means dividing said extinguishing chamber into at least one pressure accumulating chamber and one arcing chamber, said arcing chamber forming a channel through said extinguishing chamber, a stationary contact arranged in one end of the arcing chamber and a movable contract arranged to pass into the arcing chamber at its other end to engage said stationary contact, the wall of said accumulating chamber 3 having an oil-opening therein so positioned that said chamber is filled with oil to a predetermined level, thus providing a gas-filled and closed space inside the accumulating chamber above said level, means dividing the accumulating chamberqint'o at least two compartments which communicate with each other above the oil level in the accumulating chamber, the wall between the arcing chamber and the accumulating chamber having alongV the channel inle'tslots and outlet slots each communicating with one of thecompartments arranged in pairs and provided with oppositely directed check valves, so that oil can only iow through said slots from the channel through an inlet slot to the one compartment and from the other compartment through an outlet slot to the channel, said slots being covered by the movable contact as it moves into the channel.

2. An oil circuit breaker according to claim l, in which the accumulating chamber is -divided into more than two compartments which all communicate with each other above the oil level in the accumulating chamber, the -slots of one type between the channel and each compartment being alternately arranged with these of the other type. t

3. An oil circuit breaker according to claim 1, in which the stationary contact is arranged in yan enlargement in the channel.

References Cited in the tile of this patent UNITED STATES PATENTS 2,389,346 Den-ault Nov. 20, 1945 2,806,111 4Baker et al. Sept. 10, 1957 2,850,599 Forwald Sept. 2 1958 FOREIGN PATENTS 1,017,684

Germany Oct. 17, 1957 

